I. Field of the Invention
This invention relates to the preparation of nitriles and specifically to the preparation of hydrazo-bis-acetonitriles by the method of reacting an azine with hydrocyanic acid.
II. Description of the Prior Art
Hydrazo-bis-acetonitriles can be obtained by the known method of reacting an aldehyde or ketone with hydrazine and an alkaline cyanide in the presence of an acid (for example, Thiele and Heuser, Ann., 290 p. 1-40 (1896)). In a variation of this method, the aldehyde or ketone is first reacted with hydrazine thereby forming an azine and the azine is then reacted with hydro cyanic acid to form the hydrazo-bis-acetonitrile (for example, U.S. Pat. No. 2,469,358). In both methods, pure reactants are employed and each method requires the use of hydrazine, which is an expensive reactant.
One method for preparing azines comprises the oxidation of ammonia in the presence of a ketone or aldehyde by means of an oxidizing medium comprising hydrogen peroxide and cyanogen or a nitrile. This method is fully disclosed in commonly assigned pending U.S. application Ser. No. 152,413, filed June 11, 1971, now abandoned, which is incorporated by reference herein.
Another method for preparing azines comprises oxidizing a secondary alcohol in the liquid phase to form peroxide products of the auto-oxidation of the alcohol and subsequently reacting the peroxidic products with ammonia in the presence of cyanogen or a nitrile. This method is fully disclosed in commonly assigned pending U.S. application Ser. No. 230,038, filed Feb. 28, 1972, now abandoned, which is also incorporated by reference herein.
The azines prepared according to each of these methods are formed in complex reaction media which in addition to unreacted products, can also contain solvent and a carboxylic amide resulting from the transformation of the nitrile during the oxidation reaction.